


Unhealthy behaviors

by That_one_edgy_writer



Category: Undertale (Video Game)
Genre: Alternate Universe, Alternate Universe - Swapfell (Undertale), Blow Jobs, Cunnilingus, Drug Use, Ecto-Genitalia (Undertale), Ecto-Penis (Undertale), Ecto-Tongue (Undertale), Ecto-Vagina (Undertale), Gender Dysphoria, Guilt, Light Masochism, M/M, Nightmares, Other, Prostitution, Self-Esteem Issues, Self-Harm, Self-Hatred, Slut Shaming, Swapfell Sans (Undertale), Underswap Sans (Undertale), Unhealthy Coping Mechanisms, Unhealthy Relationships, Violence
Language: English
Status: In-Progress
Published: 2020-02-24
Updated: 2020-03-03
Packaged: 2021-02-28 00:54:15
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 3
Words: 3,619
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22885096
Author URL: https://archiveofourown.org/users/That_one_edgy_writer/pseuds/That_one_edgy_writer
Summary: Can Slim and Rus truly be happy if one of them is living a lie? All he wants is to please others, but what happens when it's time to focus on himself?
Relationships: Papyrus/Papyrus (Undertale), Sans/Sans (Undertale)
Kudos: 9





	1. Broken promises and passionate moments

**Summary for the Chapter:**

> When Rus feels like shit, sometimes his love comes to comfort him. Some smut and guilt, with a few broken promises.

**Notes for the Chapter:**

> No one is having a good time. Read at your own discretion but please mind the tags.

_**Sunday** _

_I do not know who I am. I know who I want to be, what I want in the future. I no longer know what I want for me._

A gentle smile, soft voice beckoning to a kind stranger, on his knees behind a random restaurant. Thankful for the simple instructions 'pull here. Touch there. Look at me.' he didn't want to think, needed a distraction, eagerly losing himself in satisfying them. Tears blurred his vision, soft moans coming out around the intrusion that gagged him, swallowing around it in a frantic attempt to relax. Gulping at the bitter fluid that shot down his throat, panting and tenderly plucking the wad of bills out of their hand. Humiliation overwhelming him, even at the gentle praise and reassurance as foreign arms dabbed at the tears and encircled him. Once he finally made his way home, he sobbed into his pillow until he could no longer breathe. 

Arms wrapping around his spouse, waiting for them to fall victim to the sweet embrace of unconsciousness before allowing tears to drip freely. Burying his skull into Slim's shoulder and wailing until his throat became raw, he was weary and humiliated and he protested against the dregs of consciousness that lingered. A losing battle that he surrendered to only when the first rays of light began to fill the room. 

**_Monday_**

_So much of who I am is dedicated to helping others and pushing them away that I can no longer distinguish the difference between me and my words, who I am and who they see me as._

  
Rus was aware that what he was doing was unhealthy, that he needed actual coping skills and to talk to someone. He ignored it once more and simply brushed his brother's suspicion off with a lazy wink, stained fingers fidgeting and plucking at his joints. Listening to him cry, speak of his lover and dig the guilt further into his soul. ''𝙄 𝙨𝙩𝙞𝙡𝙡 𝙡𝙤𝙫𝙚 𝙝𝙞𝙢. 𝘽𝙪𝙩 𝙄 𝙡𝙤𝙫𝙚 𝙂𝙧𝙞𝙡𝙡𝙗𝙮 𝙩𝙤𝙤. 𝙄𝙨 𝙨𝙤𝙢𝙚𝙩𝙝𝙞𝙣𝙜 𝙬𝙧𝙤𝙣𝙜 𝙬𝙞𝙩𝙝 𝙢𝙚? 𝙄 𝙟𝙪𝙨𝙩- 𝙄 𝙙𝙤𝙣'𝙩 𝙠𝙣𝙤𝙬 𝙖𝙣𝙮𝙢𝙤𝙧𝙚, 𝙥𝙖𝙥.” Comfort. Soft words. Hug. Repeat. Did he even love the other? Was he using Slim? It was so hard to even think of what he wanted for himself, he didn't even ask how Slim felt. Was he a bad partner?

Hours later, when his brother had left, and he was left waiting for his lover with a now empty pack of cigarettes. Left with an unfortunately empty head was when he began to scratch at his vertebrae. Pointed phalanges only halted their scraping when an almost identical pair moved them, staring into purple pinpricks of light and softly moaning when Slim drug his tongue against the dried marrow and wounds. Painful pleasure spreading at the harsh bite marks and bruises, whining at the soft kisses that trailed down his ribs, spine, then teasingly around his pelvis. It was one of those days then. He tried to reach down, to reciprocate but was pushed back down onto the lumpy couch after a while of pressing kisses and gentle nips to the other skeleton. “Wanna make you feel good too. Please” Face flushed when the nearly identical face stared back at him, shaking his skull and nibbling at the tip of his tongue before sinking twin pairs of silver canines into sensitive vertebrae. Pawing at Slim's hoodie, and shoving down his shorts to fondle at each sensitive bone, trembling when Rus kissed and sucked at the liberally dripping entrance.

“ _Fuck baby you're so good with your tongue. Tonight was supposed to be about you and you're spoiling me like this_ ” Relief flooded him at Slim's words, thankful to be helping as he tasted his lover reverently. Stifled moans against the lavender cunt grew at the simple praise, toying with the beautifully engorged nub and smiling against his pussy at the breathy moans that came from above. His eye lights morphed into heart shapes when Slim started to cry out, grinding his clit against Rus' nasal aperture. Gently prodding at the soft spot a bit further inside, shifting between eagerly lapping at his labia, rolling the soft nub between his teeth before shoving his tongue back into Slim's cunt and gasping when Slim came with a gush of fluid against his face. “ _Shit_!"

He yelped when Slim pressed him gently against the couch once more, shaking at the inviting mouth pulling down the waistband of his shorts and boxers. Soft moans and muffled noises from his lover sucking on his member spread throughout the small apartment, his skull falling back onto the cushion when he placed a hand on his iliac crest to still him. "Please. Feels so good, 'm close." Rus whined when Slim pulled back, crying out when he came, tangerine-colored seed covering his love's face, voice creeping higher when the other wrapped his tongue around him once more. His vision left him at the fifth orgasm, dyeing his love's ribs and soul and- a sixth without even being grazed. Once he settled enough to regain his sight, he was greeted with the image of Slim tucking him into their bed and placing a kiss to his forehead. "𝘐 𝘭𝘰𝘷𝘦 𝘺𝘰𝘶. 𝘐'𝘭𝘭 𝘣𝘦 𝘣𝘢𝘤𝘬 𝘣𝘦𝘧𝘰𝘳𝘦 𝘺𝘰𝘶 𝘸𝘢𝘬𝘦 𝘶𝘱, 𝘱𝘳𝘰𝘮𝘪𝘴𝘦." 

**_ ~~Tuesday~~ _ **

~~_He's not here. Why isn't he here, I need him._ ~~

Slim was not there the following morning, nor the morning after that. Of course not. Rus was being ungrateful. Slim was a grown monster and could handle himself perfectly fine, that didn't mean Rus didn't worry though. Didn't mean he wasn't allowed to want, to yearn for his embrace.


	2. Fears and... Guilt?

**Summary for the Chapter:**

> Seems that Slim and Rus have some communication issues, but surely that won't reflect poorly on their relationship? A peek at Rus' intrusive thoughts  
> (Rus is my interpretation of fell swap papyrus, Slim is my interpretation of swap fell paps. Just to clear that up for you in case things were a bit confusing.)

**Notes for the Chapter:**

> A bit of what could be seen as guilt tripping, just a really fucked up relationship dynamic in general

~~_**Wednesday** _ ~~

~~_I need him to tell me I'm not useless. I need him to tell me I'm good, that I'm not a failure. I can't function on my own. I need someone to tell me what to do. How to do it._ ~~

~~𝙏𝙪𝙚𝙨𝙙𝙖𝙮 𝙒𝙚𝙙𝙣𝙚𝙨𝙙 ** _ay_**~~ 𝙏𝙝𝙪𝙧𝙨𝙙𝙖𝙮

𝘐 𝘧𝘦𝘦𝘭 𝘯𝘦𝘨𝘭𝘦𝘤𝘵𝘦𝘥 𝘸𝘪𝘵𝘩𝘰𝘶𝘵 𝘱𝘩𝘺𝘴𝘪𝘤𝘢𝘭 𝘤𝘰𝘯𝘵𝘢𝘤𝘵, 𝘰𝘳 𝘮𝘺 𝘭𝘰𝘷𝘦𝘳'𝘴 𝘦𝘮𝘣𝘳𝘢𝘤𝘦. 𝘛𝘩𝘦𝘴𝘦 𝘢𝘳𝘦 𝘭𝘶𝘹𝘶𝘳𝘪𝘦𝘴 𝘐 𝘬𝘯𝘰𝘸, 𝘣𝘶𝘵 𝘐 𝘩𝘢𝘷𝘦 𝘣𝘦𝘤𝘰𝘮𝘦 𝘢𝘤𝘤𝘶𝘴𝘵𝘰𝘮𝘦𝘥 𝘵𝘰 𝘩𝘢𝘷𝘪𝘯𝘨 𝘩𝘪𝘮 𝘩𝘦𝘳𝘦 𝘰𝘯 𝘣𝘢𝘥 𝘥𝘢𝘺𝘴. 𝘛𝘰 𝘴𝘵𝘰𝘱 𝘮𝘦 𝘧𝘳𝘰𝘮 𝘵𝘩𝘪𝘯𝘬𝘪𝘯𝘨. 𝘓𝘰𝘴𝘪𝘯𝘨 𝘮𝘺𝘴𝘦𝘭𝘧. 𝘐 𝘧𝘦𝘦𝘭 _worthless, knowing that my cowardice keeps me from speaking with him about this. Telling him that I wasn't him to myself. That I offer myself to strangers for money out of necessity, afraid to get an actual job._

He grew anxious on the third. Rus remained in the bed, bare and cold without his partner to come and hold him, to tell him that he was okay. To take his focus away from his body, to stop him from scratching at his shoulder blades, his arms, to tell him that he still adored him. To tell him that he was needed, that he had a purpose. He tried to text, to call, but each time it went ignored he lost hope that his love would come home. Only greeted with one-word replies and an image, a splotch of red cum dribbling off of Slim's tongue next to a brightly glowing crimson member. The caption made his soul feel as if it had been dipped in ice water '𝘸𝘰𝘳𝘬𝘪𝘯𝘨. 𝘚𝘰𝘶𝘯𝘥 𝘧𝘢𝘮𝘪𝘭𝘪𝘢𝘳 𝘣𝘢𝘣𝘦? 😘 𝘐'𝘭𝘭 𝘣𝘦 𝘩𝘰𝘮𝘦 𝘴𝘰𝘰𝘯'. 

Soon could mean anywhere between tonight and next month. He didn't respond. Only pulling on a soft pink turtleneck and a pair of sweatpants before going to the small kitchen pair chugging what remained of the milk, crossing out two days on the small diary that he was gifted and flinging it back under the sink. Only two small notes added next to it.

_I am:_

  * _Weak_
  * _Disgusting_
  * _Useless_



_I need him._

He couldn't sleep. Even after his love returned with a few bundles of bills and yet another promise to stay, soft words murmured to him as the other wrapped his arms around him and fell asleep in their bed. Shared again, for how long? It didn't matter. He was home now. Rus could be better for him, try to care for him more and keep him from leaving. He needed him to stay. Desperately. He couldn't be left alone again. He didn't want to 𝘩𝘶𝘳𝘵. At least not in this way, it didn't matter if he came off as clingy or annoying.

Quietly, he switched on the TV and stared at the image of Napstaton dancing and singing some new hip hop song that Black and Blue had been gushing about. Distantly, he wondered if he should call them before deciding that it would be too much work to carry a conversation with either of them. Sluggishly, he switched the channel to some soap opera and staring at it blankly. This was fine. He was fine. Something still felt off about how his clothes fit, his shoulders, pelvis, even his voice. But it was fine. He'd live. 

His hands shook as he stepped outside, fiddling with his lighter before he took a drag from the bent cigarette between his teeth. Curiously, he watched the smoke lazily curl away from him, through his shirt and out of his sockets. Rus stared up at the sky, brilliant lavender and vermillion hues blurring together as tears stung at the edges of his sockets. It didn't matter how many times he'd seen the sun setting and rising atop Mount Ebott, seeing it as a reminder that he was here, breathing fresh air and listening to the soft sounds of animals that never would have even survived underground was something that he never could ignore. He stepped back inside and 

_**Friday** _

_Often I am reminded that my life is insignificant compared to the people I attempt to console, expendable by the authority that is supposed to accept and protect us._

The soft tapping of a pen against him, a pair of lanky arms wrapped around him. "...Slim?" A grunt, arms tightening around him in place of a verbal answer. "I... Would'ya still want me if I wasn't a guy?" Silence. He could feel the other's gaze against the back of his skull, judging. "It's just. what if I don't like bein' a guy? What if I'm not supposed to-" A soft chuckle, the other skeleton's teeth pressing against his own in a chaste kiss. "Had me worried there for a bit, babe. You're fine. You're not one of those 𝘧𝘳𝘦𝘢𝘬𝘴." 

Rus nodded at his partner's words, wincing as he practically hissed out the last sentence. Pressing a kiss to the other's cheek, both slipping into the shower and feeling water rush over their bones. He pressed himself against his love, teeth gently pressing together and tongues tangling languidly. They reluctantly broke away from each other when the water grew too hot, a string of russet saliva stretching between them and breaking. Slim chuckled when he ran a lathered rag over his ribcage, Rus' face flushed at the soft groans that came from the thin skeleton as he washed his spine. He made a soft pleading noise when Slim clutched onto his shoulder blades, dragging the cloth gently across the bones inside of the other skeleton's pelvis and biting down on his clavicle with a possessive growl. Watching his partner fall apart right in front of him made his own heated magic swirl around inside his pelvis. 

When Slim stood once more, allowing the water to rinse off the suds and immediately scrubbing at his pelvis Rus placed a hand over his mouth. Wonderfully filthy words whispered next to his skull mixed with the delicious pain of the other's sharpened fingertips had him resting his forehead on his love's shoulder. "Such a good boy for me, aren't you? You're so cute like this, all whiny and desperate. Does my good little slut, want me to use him like a cock sleeve? Wanna feel me poundin' into ya, cummin' in ya, markin' ya as mine? Bet ya want my cum drippin' outta you, wanna see just how many times I can get ya to tell me you're a good little cockwhore 'n get ya to _beg_ for it? You're close, ain't you? Didn't even form anything 'n you're squirmin' n' moanin' like a bitch. _My_ bitch." Soft moans and harsh panting filled the bathroom, bones rattling together as his orgasm overtook him and left him a shaking pile of bones.

Thankfully, Slim didn't try to stimulate his oversensitive magic after wiping down his trembling bones, drying him off and carrying him into their bedroom. A soft pink robe was draped across him, loosely tied and the purple fur that adorned the sleeves and bottom matching the one that Slim pulled on. "You didn't have to-" He was shushed by a finger against his teeth, his lover picking him up and pressing another kiss against him. " _Listen_ to me, Slim. Have- have I been a bad boyfriend?" The other skeleton raised an eye ridge at the query, peppering soft kisses against his face and tilting his head in confusion. "Why'd you think that?" He almost looked... Hurt? No, that couldn't be right. Slim didn't apologize, and he certainly didn't admit to any guilt. Rus shrugged his shoulders, his face a mask of indifference as he spoke. "Dunno. Feels like the only time you're happy around me is when we fuck or when you go out for the night."

Slim paused in petting Rus' skull, looking down at the skeleton in his arms like a kicked puppy. Sitting him down on the edge of the bed and scooching next to him, tears welling up at the edge of his sockets. "Why do you only ever bring that up after we have sex?" Rus didn't interrupt, steeling himself for the impending argument and trying not to let his own tears fall as well. "You think everyone wants to hurt you, but maybe, _maybe_ I just want to make you happy." A large bone crashed through the small dresser that Rus had taken up painting, several more smashing into it even after Rus began to curl in on himself. "I have friends that _aren't_ you, y'know. WOULD IT MAKE YOU FEEL BETTER IF I JUST SCRATCHED AT MY BONES 'TIL NOTHING'S LEFT? IS THAT IT!?" Rus whimpered, hands over the sides of his skull and desperately trying not to think, to breathe. "I didn't think that's what you thought I just-" Slim held him close, hands stroking at his back as he listened to the other's tearful apologies. "It's alright, I know you didn't mean it. We'll go out tomorrow and do some shopping, and maybe go out for a bit." Rus nodded and allowed his love to soothe him to sleep, a tight grip on his robe even after he was tucked into the bed and the warmth of his lover didn't leave him. 

His slumber did not last long, restless dreams plagued by an apathetic face, a makeshift spear plunging into his brother's soul, and a blue and purple striped sweater quickly morphing into his love screaming at him. Telling him that he was a _freak_ , a _mistake_ , a _disgusting waste of space_. They- _He. ~~It didn't matter that using that pronoun made them want to cry, to curl into a ball and call their brother and finally move somewhere where they won be endlessly screamed at. It's what Slim wanted. It made Slim happy. That's all that mattered~~_ gingerly crawled out of bed and into the living room, sprawling out across the sofa and staring up at the ceiling with wet sockets. 

Things would get better, go back to usual. Sometime... Right? 


	3. Self-discovery

**Summary for the Chapter:**

> Rus finds out a few unwanted things about himself, and his brother starts to suspect something is up

**Notes for the Chapter:**

> Sorry about taking so long to update, I'm trying to get a schedule down I swear. I hope you're doing well in these stressful times.

_**Saturday** _

_I am terrified of death to the point that it is something I fret over every day, despite it being an inevitable force that consumes all. I despise and love my body. Crave to remove parts that will make me whole without even knowing if my life will last long enough to afford such a thing. The knowledge that I could be murdered for existing makes me numb. I am afraid to feel. To speak._

Rus felt...nice. It was different. He liked the quietness of the restaurant, the way that soft lighting shined off of his lover's false teeth was enchanting. Slim's bones were frail and brittle but somehow managed to fill out the dress shirt that wore in a way that had Rus itching to curl up next to and just stare for hours. It was a special occasion when he broke out the plum-colored socket liner, even more when they went anywhere that wasn't McDonald's. Slim gave him flowers, _live flowers._ It had been months since they'd even visited their brothers, the concerned faces and prying questions being enough of a deterrent to discourage Slim from visiting again.

He liked the way that his sweater rubbed against his bones, pleasant and soft and comfortable. Slim said it was too feminine, but he didn't want to take it off. Didn't want to stare at his bones and have them outlined in a shirt that felt wrong, accentuating parts of him that he'd rather risk falling against the edge of the sink than see when he took showers. Rus was in the middle of shoveling another forkful of ravioli into his mouth when Slim spoke, his metaphorical stomach dropping at the words that came from his lover's mouth. "I wanna collar you."

_Commitment. Ownership._

"...no." He wanted freedom, to contribute to something on his terms.

Even when Slim was throwing things when they got home, telling him just how selfish denying him was, he stood his ground. It felt good. Empowering. It didn't matter when Slim stormed out, slamming the door behind him and splintering the frame. Nor did it matter when he too, walked out of the door and fell onto his brother's sofa. The indignant screech that left a half-naked Grillby was worth the hug that came from his brother, comforting words coming from the smaller skeleton as Rus began to hurriedly explain while trying to breathe between sobs.

**_ Sunday again. _ **

_I do not want professional help. I wish not to burden others with the cost, nor to become more of a financial concern than I currently am. I laugh and smile and lose myself in brief moments of passion, but none of these things bring fulfillment._

"𝙂𝙧𝙞𝙡𝙡𝙗𝙮, 𝙄'𝙢 𝙬𝙤𝙧𝙧𝙞𝙚𝙙 𝙖𝙗𝙤𝙪𝙩 𝙩𝙝𝙚𝙢. '𝙍𝙪𝙨 𝙞𝙨𝙣'𝙩 𝙜𝙚𝙩𝙩𝙞𝙣𝙜 𝙗𝙚𝙩𝙩𝙚𝙧 𝙨𝙩𝙖𝙮𝙞𝙣𝙜 𝙬𝙞𝙩𝙝 𝙝𝙞𝙢." 

Ouch. Talk about being a burden, okay, maybe that was just the alcohol that they'd stolen from beneath his brother's bed talking and making them overemotional. 

_"I know that you are worried about your sibling, but they need to learn how to stand up on their own without your help, love."_

They shuffled into the kitchen and grabbed a box of cereal, petting the small cat that climbed onto the counter as they shoved handfuls of cereal into their mouth. Marshmallows. So his brother knew that he would be coming back. How long had he prepared for their arrival, did he expect bruises, or maybe a cracked pelvis to be the last straw? They waited for the not so hushed voices to die down before sitting in one of the kitchen chairs and checking their phone. The amount of missed calls and text messages went ignored, and they opened up the notes app that they had spent so long locking and constantly changing the password to.

Names?

  * Helvetica
  * Ophelia
  * Cancione
  * Allura
  * Ameliana



The app was quickly closed at the sound of not so subtle footsteps. The first three names sounded okay, though Mutt was a go-to if anyone ever decided they cared enough to pry. " _ **OH. I didn't know that you were awake, Rus. I hope we didn't wake you"**_ They shrugged and shoveled more of the cereal into their mouth, messily crunching down and noting with no small amount of disdain that there was no anger or disgust on his face, only pity as if he didn't know why 'Rus hardly ever ate. Rus was already enough of a financial burden and they didn't need to add onto it by eating everything in sight. The money problems that both their brother and Rus had were already bad enough. "don't worry about it. just couldn't sleep" not through the sounds of Grillby's desperate pleas, moaning and begging for their brother instead of- no. Grillby wasn't their husband anymore.

* * *

_The feeling of having their throat fucked raw by a stranger in the middle of a dark alleyway was as cathartic as it was pleasurable, the soft moans that they were dragging out of the human that could probably snap their neck if they really wanted to sent a spark of sharp pleasure down their spine and straight to their pelvis. The eager mouth beneath them seemed to enjoy it, gripping onto their thighs and pulling their crotch flush against his face. the fingers that were slowly sliding up and trying to prod at their asshole were almost swatted away, the feeling of warmth and harmlessly flickering flames dipping down to tease their cunt and stars they were so close just a bit more- a low keen came from their mouth when he pulled his hand away, using it to slowly slide into the much tighter entrance at the same time the mouth below them bit their clit and the hand around their throat held them in place while they-_

Rus groaned when they woke up, shoving the sheets between their legs and rolling over. They were way too tired for that, it could wait until they showered. They shivered when the AC turned on, bundling themself up in the blankets and pillows once more with a frustrated huff. Being awake was using far too much energy and now they were fucking _cold_. They groaned and pulled a pillow over their face to try and muffle the noise of the vacuum.


End file.
